Radius PDR 121, Инструкция по установке и эксплуатации

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RADIUS
Product Description
PDR 121
iom_pdr121_04_r02.doc Rev 02 Page 42 (67)
Example 1
Is the radio link theoretically possible? Calculation of fade margin FM;
Distance
= 3 miles (5km)
Antenna height 1 = 65 feet (20 meters)
Antenna height 2 = 16 feet (5 meters)
Radio Tx Power = 33 dBm (2W)
Radio Rx Sensitivity = -110 dBm
Frequency = 456.000 MHz
Antenna Gain 1 = 3dBd
Antenna Gain 2 = 6dBd
Cable / Connector losses = 4 dB total
FM = ?
A = 117 + 40 x log 3 + 20 x log 456 – 20 x log(65 x 16) = 129 dB
FM = Srx + Ptx + Gtx +
A + Grx – Cl ->
FM = 110 dBm + 33dBm + 3dBd – 129dB + 6dBd – 4dB = 19dB
The fade margin is 19 dB, which is an acceptable level. The radio link should be possible.
Example 2
How high should the master antenna be mounted?
Distance
= 12.5 miles (20km)
Antenna height 1 = X
Antenna height 2 = 64 feet (20 meters)
Radio Tx Power = 33 dBm (2W)
Radio Rx Sensitivity = -110 dBm
Frequency = 142.000 MHz
Antenna Gain 1 = 3dBd
Antenna Gain 2 = 6dBd
Cable / Connector losses = 4 dB total
Fade Margin = 20dB
Calculating highest allowed over air attenuation:
FM = Srx + Ptx + Gtx + A + Grx – Cl ->
A = Srx + Ptx + Gtx + Grx – Cl – FM ->
A = 33dBm + 3dBd + 6dBd – 4dB – 20dB = 128 dB ->
Calculating antenna hight X using A from above:
A =128 = 117 + 40 x log 12.5 + 20 x log 142 – 20 x log( X x 64) ->
20 x log (X x 64) = 117 + 40 x log
12.5 + 20 x log 142 – 128 ->
20 x log (X x 64) = 75.9 ->
X = (10
75.9/20
) / 16 = 97.5 feet = 30 meters